NFC technology allows for wireless communications between a mobile device (e.g., an NFC-enabled mobile phone or a smart card with an NFC/RFID tag) and an NFC reader (e.g., in a point-of-sale terminal or another mobile device) over a distance of several centimeters or less. To establish an NFC connection between an initiator device and a target device, both devices may follow a number of NFC standards (e.g., the ISO/IEC 18092 and ECMA-340 standards). Currently, there are two NFC communication modes: passive communication mode and active communication mode. In the passive communication mode, the initiator device generates a carrier signal and the target device sends data to the initiator device by load modulating the initiator device's carrier signal. Because the target device does not generate its own carrier signal, the target device may operate in the passive communication mode without transmitting power. In the active communication mode, both the initiator device and the target device communicate by alternately generating their own carrier signals, thereby distributing power consumption between the initiator and target devices.
Because the target device in an NFC passive communication mode may consume significantly less power, the passive communication mode is often used when the initiator device has a plentiful power supply (e.g., an electrical outlet) and the target device has a limited power supply (e.g., a battery) or no power supply. However, because passive load modulation depends upon the inductive coupling between the respective antennas of the initiator device and the target device, the effective modulation associated with data transfers using passive load modulations may be lower than data transfers using the active communication mode or direct power transmission. In addition, the desire to perform effective data transfers using passive load modulation may undesirably limit the extent to which the antenna of the target device can be reduced (e.g., because reducing the size of the target device's antenna may decrease the amount of inductive coupling between the target device and the initiator device).
Accordingly, there is a need to increase the power level of signals exchanging data in response to a request for the NFC passive communication mode.